Cold-forming involves the manufacture of a variety of metal parts and component, such as screws and bolts, at room temperature. The cold-forming process starts with a coil of wire or rod that is fed into a cold header. The cold header cuts the wire at an appropriate length and progressively forms the cut-off portion or slug into a specific shape through a series of punches and dies.
Cold-forming provides several advantages over other methods for manufacturing similar parts. Cold-forming wastes less materials because almost all of the material is reshaped to form the finished part, leaving virtually no scrap behind. The cold-formed part is stronger than parts made from other manufacturing processes because cold-forming causes the grain flow to follow the part configuration. Cold-formed products have consistent strength and dimensional accuracy and maintain a good appearance and finish. Other manufacturing processes require a finishing operation. Cold-forming also has phenomenal production rates when compared with other production processes and is the fastest production process for many parts. Additionally, cold-forming permits the combining of separate parts into a one-piece component that is stronger than the combined separate parts and reduces assembly operations required of other manufacturing processes.
Cold-forming is performed in a cold header or cold former in reference to the fact that they form steel into specific shapes at room temperature. Coiled wire or rod is fed into the cold header. The cold header cuts the wire or rod into cutoff slugs or blanks of a specified amount. The cold header forms these cut-off slugs into the specific shape of the final product. A blow or ram side of the cold header forces the cut-off slugs into a die in the die side of the cold header and causes the slug to conform to the shape of the die.
The ram side includes a sleeve assembly that is secured to a bolster plate on the ram side. The sleeve assembly includes a sleeve that surrounds packing and a frequently replaced insert pin. The ram side and the sleeve assembly move between a back position and a forward position while the die side of the cold header remains stationary. In the back position, the ram side is separated from the die side of the cold header, and a cut-off slug is positioned between the insert pin of the sleeve assembly and an opening to the die on the die side of the cold header. In moving to the forward position, the insert pin of the sleeve assembly rams the cut-off slug into the die on the die side of the cold header. As the insert pin pushes the cut-off slug into the die, the slug is extruded to the shape or diameter required. When the ram side returns to the back position, an ejector pin ejects the slug and completes the cold-forming operation. A cut-off slug may require a succession of cold-forming operations for a completed part.
During these cold-forming operations, insert pins commonly break and packings become damaged, requiring replacement. The current design of the blow assembly requires that the entire sleeve assembly be removed from the bolster plate on ram side of the cold header in order to replace the insert pin and the packings. After the sleeve assembly is removed and replaced, a significant time is spent in re-adjusting the location of the sleeve. The current sleeve assembly wastes time and money because the current sleeve design does not provide for part replacement without removing the entire sleeve assembly.
Moreover, the current sleeve assembly presents certain cost inefficiencies. The present cold-headers require that a new sleeve and insert pin be made and kept in inventory for each new job. New jobs require different insert pins because the diameter of the insert pin changes for different jobs. The sleeve assembly remains assembled in inventory because the sleeve, the packing and the insert pin are all part specific. Thus, the present sleeve assembly is cost inefficient because the current sleeve assembly design requires a large inventory of sleeve assemblies for a cold-forming manufacturer.